Can't speak to what's going on elsewhere, but I have to say that in my neck of the woods, the USA, I've found having ADS-B TIS-B services in the cockpit a real game changer. Not to mention eye opener. I used to pride myself on a sharp lookout, but now I realize how much I, and everyone else for that matter, has been missing. With the ADS-B mandate deadline coming the end of 2020, having nearly ubiquitous equipage will be almost a reality (there are some exceptions). Of course, many will cheap out and not have ADS-B "in", only the mandated "out", but once you fly with TIS-B services it is hard to go back to not having them, you feel really blind.
I've been using GTX345 sourced TIS-B, both as displayed on the GNS420 and on the tablet I often fly with, since Sep 2017. It has become part of my scan, and when something or someone starts to get close on the traffic display my external scanning definitely gets more focused on that part of the sky. I'm seeing more, faster, than I ever did.
On a somewhat humorous note, many US pilots, in a typical display of US "lese majeste", when maneuvering and communicating around uncontrolled airfields, will now say "I've got you on the fishfinder" as part of the general aviation pilot patois. I prefer "traffic display" or "TIS-B", and no substitute for the Mark One Eyeball, but still it's nice to know you are being seen somehow.
Of course it is not all perfect. I've had aircraft pop up out of valleys and from behind hills at very close range and surprise both me and the GTX345, which will only announce "Traffic! Traffic!" when so surprised. But it's so much better than not having it at all.